Removing Prop Shaft While Still In the Water - SailNet Community
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post #1 of 23 Old 08-27-2009 Thread Starter
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Removing Prop Shaft While Still In the Water

I am in the process of replacing my engine in my Alberg 30. Because of slight differences in the footprint of the new engine vs. the old one, I have to remove the old flexible coupling the is on the prop shaft and replace it with a new one. This will require getting the new coupler fitted and faced. If anyone has tried this, you know how tight they are on the shaft. Anyway, what I would like to do, once I get the coupler off, is to remove the shaft from the boat while it is in the water. Has anyone tried this before? I visualize getting a cap that I can screw on over the log side of the packing gland and sliding the shaft out thru the cutlass bearing. In the event that I can't get the coupling off, I would try to take the prop off and then remove the shaft thru the inside of the boat (remember, the engine is NOT installed at this time). In either case I would need a cap the same size as the log side of the packing gland. For a 7/8 inch shaft, does anyone know what size that would be? Any advice or ideas are more than welcome...

Bob
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post #2 of 23 Old 08-27-2009
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This is a pretty risky thing to be trying.. A hell of a lot of water is going to want to come into the boat during the removal.. this is not going to be as quick as a transducer/plug swap....

I think you're asking for trouble.. but if I was to try this I'd simply get a spare piece of 7/8" shafting and slide it into the gland as the prop shaft is pulled through.

But again, this is really a haul-out job..

Ron

1984 Fast/Nicholson 345 "FastForward"

".. there is much you could do at sea with common sense.. and very little you could do without it.."
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post #3 of 23 Old 08-27-2009 Thread Starter
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Yeah, I can see where your coming from... but my idea is to pull the shaft from the prop end and before it is all the way out, replace the packing side of the gland with a cap. If I have to pull the shaft into the boat, then would stuff a rag or something in the log at the back end before the shaft is completely removed and then after it is all the way out put the cap on. Only problem is finding a cap that will thread on to the log end of the packing gland.
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post #4 of 23 Old 08-27-2009
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I'm getting the willies just thinking about this -- talk about getting waaaay out on the limb!

If you do take a stab at this, do it in shallow water and by all means have someone filming it... Strike that last bit -- your insurance company may subpeona the film to negate your claim

Seriously though, why take the chance? It sounds like you're planning on being shaftless for a fair amount of time, and the gremlins are going to be working overtime trying to figure out how to defeat your best laid plans.

You could just bang a wooden plug into the hole (consider it a dress rehearsal for a mid-ocean damage control evolution), and then drive it back out with the newly finished shaft. That'd be a little faster than fussing around trying to get a threaded cap onto that gushing geyser.

Anything you could do to raise the stern (and thus lessen the ambient water pressure) would probably be a good idea as well. The closer you can get it to the surface, the lesser the pressure will be.

Do think long and hard before you actually pull the shaft out. Consider everything that could potentially go wrong and take countermeasures to mitigate the risk.

Hope it all comes out (and goes back in) well.
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post #5 of 23 Old 08-27-2009
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Originally Posted by examiner View Post
Yeah, I can see where your coming from... but my idea is to pull the shaft from the prop end and before it is all the way out, replace the packing side of the gland with a cap. If I have to pull the shaft into the boat, then would stuff a rag or something in the log at the back end before the shaft is completely removed and then after it is all the way out put the cap on. Only problem is finding a cap that will thread on to the log end of the packing gland.
It will be a problem finding a match.. (btw - have you noticed that so far it's 2-1 against doing this in the water???) Pipe caps are tapered thread, the packing gland is not. If you're absolutely bent on doing this, maybe have a rubber disc cut to fit inside of your existing packing gland nut, and slip it into the nut and reinstall it (assuming that you have the time.) at least then you'll know the thread's a match. Suck it down tight and the leak should be minimal..

It's still a bad idea

Ron

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post #6 of 23 Old 08-27-2009 Thread Starter
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Yep, yep.... now it's 3 to 1 Looking more and more like I'm gonna hafta have her hauled...

Bongo Bob
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post #7 of 23 Old 08-27-2009
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.. actually that'd be 3-0... good call!

Ron

1984 Fast/Nicholson 345 "FastForward"

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Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)
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post #8 of 23 Old 08-27-2009
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OK, just to be contrarian (and to see what sort of abuse I get from those wanting you to spend money on an unneeded haulout): First: Get a short piece of the same size shaft from the prop shop that's going to be facing the flange to the shaft (are you sure you need that? What sort of flexible coupling are you going to use between the shaft and the tranny?); if it's not a prop shop but a regular machine shop then stop by the local prop shop and get a short length of the same sized shaft. They have lots of bent shafts lying around and you only need a short length so exactly straight isn't important--- proper diameter is. Round the edges of the outboard end (the end that's going to going into the hole once you pull the shaft into the boat) so it doesn't cut the packing when you slide it in. Jump into the water and remove the prop and make sure the shaft is free of zincs etc. and fairly clean (no marine growth). Pull shaft from inside the boat and replace with the stub shaft. You probably won't need to tighten the gland but if it drips too much then do so. Tie a restraining line or cord around the gland and over the end of the shaft stub to hold it in the hole. I doubt you will get much water into the bilge. I've replaced gate valves (OH shutter, the horror of it... gate valves on a boat) in the water and this is easier; so be prepared, keep your cool and all will go well.

You are going to need the boat in the water with the shaft in the hole to properly align the shaft and the engine/transmission, so reverse this process when ready to install the engine prior to setting the engine onto the mounts.

Bests,
Wiley
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post #9 of 23 Old 08-27-2009 Thread Starter
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Hmmmm.... now it''s 3 to 2... I will be using a R&D flex coupling between the shaft coupler and the tranny. I had originally intended to use the existing flex coupling (older rubber and metal coupler) with the new flex coupling but it pushed the shaft back too far and interfered with the rudder. Could not use the existing flex coupler as it was not thru bolted and I would have had to pull the tranny flange off to capture the bolts that would go into the old coupler. Putting the R&D flex coupler between them would have fixed THAT problem. Didn't want to mess with the brand new motor/tranny, though.

Bongo Bob
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post #10 of 23 Old 08-27-2009
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I certainly wouldn't

I wouldn't attempt this, but I think it can be done. If you have to pull the shaft from the inside, I would get me a couple of wax toilet bowl rings, and stuff them in the shaft log, as you pull the shaft. This will not make it leak proof, but will certainly slow it down a bunch, till you get something more solid on the inside. Then you slide the new shaft back in, the shaft will push the wax out, no problem. One thing for sure, keep us posted on how you go about it, and how it works out.

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